If an email sent to an own domain (i.e. not a free webmail or an ISP-provided email address),
say, [email protected] (I do hope that's not a real domain name; I daren't check at work), doesn't work, try sending it to [email protected] instead. A lot of web hosts make you get a 'postmaster' address if you have the domain name with them too, so you know it won't bounce. Useful to know if you were given the wrong spelling of the first bit by someone sausage-fingered and you can't work out the correct spelling (like if it's someone's unusual name).

Actually, this is probably a bit esoteric, but it did come in useful today. Address given was [email protected], it bounced, [email protected] didn't.
( Bob Todd whee, Tue 8 Jun 2010, 13:55, 2 replies, latest was 15 years ago)

The address may exist but it could well go nowhere...

(MrOli is ugly, but in the morning you will be sober, Wed 9 Jun 2010, 12:59, Reply)

Indeed.
Every domain, bar one, the postmaster account is virtually never checked. Also, addresses like postmaster@, admin@, root@, info@ are very prone to spam, so if they are in use often have much more aggressive spam filtering and/or are prone to having full mailboxes hence more likely to bounce.
( Sextant goes to him is emotionally erect, on this day, Sun 20 Jun 2010, 3:42, Reply)